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====== Theory of spectroscopy, dynamics and numerical methods for complex materials ====== ===== Talks ===== ==== X-ray spectroscopy - summer school lecture ==== [[https://podcasts.apple.com/de/podcast/uxss-theory-of-x-ray-spectroscopy/id511971711?i=1000118276233&l=en|Available on Itunes]] [[http://www-conf.slac.stanford.edu/uxss/2012/|UXSS, Stanford]] [[http://hercules-school.eu/|Hercules, Grenoble]] [[https://success-2022.sciencesconf.org | success 2022]] [[https://success-2017.sciencesconf.org | 2017]] [[https://success-2014.sciencesconf.org | success 2014]] A 1 1/2 hour lecture introducing the basics of various core level spectroscopies (XAS, RXD, RIXS) on transition metal compounds. The lecture starts by introducing (correlated) transition metal compounds, why they are interesting, what are the open questions and how one can use core level spectroscopy to gain more insight into these materials and their physical properties. The lecture focusses on the relation between x-ray absorption (XAS), resonant elastic x-ray diffraction (RXD) and resonant inelastic x-ray scattering (RIXS). In the first half the basis properties of XAS are discussed, introducing the optical selection rules and the difference between band/continuum excitations and excitons. It is briefly discussed how one can calculate XAS spectra, as well as the sum-rules relating the integrated intensity to ground-state expectation values. Polarization dependence is discussed by introducing the optical conductivity tensor (at x-ray frequencies), which then can be naturally extended to the scattering tensor. Dynamical effects in diffraction are discussed. The lecture ends with a discussion of resonant inelastic x-ray scattering. {{ :talks:haverkort_hercules_2017.pptx |Hercules 2017 [86.8 Mb]}}\\ {{ :talks:haverkort_hercules_2015.ppt |Hercules 2015 [76.1 Mb]}}\\ {{ :talks:haverkort_success_day1.ppt |Success les Houches 2014 day 1 [26.4 Mb]}}\\ {{ :talks:haverkort_success_day2.ppt |Success les Houches 2014 day 2 [49.7 Mb]}}\\ {{ :talks:haverkort_success_2017_01.pptx |Success les Houches 2017 part 1 [32.7 Mb]}}\\ {{ :talks:haverkort_success_2017_02.pptx |Success les Houches 2017 part 2 [57.8 Mb]}}\\ === Additional slides with background information for a related Quanty tutorial === Several slides providing background information on how to preform calculations related to spectroscopy for many body systems. {{ :talks:haverkort_intro_many_body.pptx | Introduction to many body physics and the computational complexity of the general problem [19.3 Mb]}}\\ {{ :talks:haverkort_intro_quanty.pptx | Introduction to Quanty as a tool to solve general problems in many body physics [2.0 Mb]}}\\ {{ :talks:haverkort_intro_spectroscopy.pptx | Introduction to spectroscopy and response functions [10.9 Mb]}}\\ {{ :talks:haverkort_quiz_spectroscopy.pptx | Quiz on the interaction between photons and matter (H atom) [7.5 Mb]}}\\ {{ :talks:haverkort_coulomb_repulsion.pptx | Coulomb repulsion and Slater integrals [1.3 Mb]}}\\ {{ :talks:haverkort_crystalfield_expansion_renormalized_sphericalharmonics.pptx | Crystal-Field theory and potentials [0.9 Mb]}}\\ {{ :talks:haverkort_dft_to_tightbinding_ligandfield.pptx | Tight binding parameters from density functional theory - down-folding and Wannier orbitals [46.7 Mb]}}\\ ==== Introduction to spin-orbit coupling - summer school lecture ==== Two lectures of 1 hour introducing spin-orbit coupling in solids. Starting from Dirac equations the relevant relativistic interactions are discussed. Spin-orbit coupling in atoms is treated, including g-factors, magnetic moments and magnetic susceptibility. Next the spin-orbit interaction in a crystal-field picture is introduced including the effective angular momentum of the //t<sub>2g</sub>// sub shell. In the final part this is used to create a tight binding Hamiltonian which can describe Rashba splitting and topological states of mater. {{ :talks:haverkort_spin-orbit.ppt |Spin Orbit 2014 [85.19 Mb]}} {{ :wiki:head.gif?nolink |}}